//
// detail/win_global.hpp
// ~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef ASIO_DETAIL_WIN_GLOBAL_HPP
#define ASIO_DETAIL_WIN_GLOBAL_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "asio/detail/config.hpp"
#include "asio/detail/static_mutex.hpp"
#include "asio/detail/tss_ptr.hpp"

#include "asio/detail/push_options.hpp"

namespace asio {
    namespace detail {

        template<typename T>
        struct win_global_impl {
            // Destructor automatically cleans up the global.
            ~win_global_impl() {
                delete ptr_;
            }

            static win_global_impl instance_;
            static static_mutex mutex_;
            T *ptr_;
            static tss_ptr <T> tss_ptr_;
        };

        template<typename T>
        win_global_impl<T> win_global_impl<T>::instance_ = {0};

        template<typename T>
        static_mutex win_global_impl<T>::mutex_ = ASIO_STATIC_MUTEX_INIT;

        template<typename T>
        tss_ptr <T> win_global_impl<T>::tss_ptr_;

        template<typename T>
        T &win_global() {
            if (static_cast<T *>(win_global_impl<T>::tss_ptr_) == 0) {
                win_global_impl<T>::mutex_.init();
                static_mutex::scoped_lock lock(win_global_impl<T>::mutex_);
                if (win_global_impl<T>::instance_.ptr_ == 0)
                    win_global_impl<T>::instance_.ptr_ = new T;
                win_global_impl<T>::tss_ptr_ = win_global_impl<T>::instance_.ptr_;
            }

            return *win_global_impl<T>::tss_ptr_;
        }

    } // namespace detail
} // namespace asio

#include "asio/detail/pop_options.hpp"

#endif // ASIO_DETAIL_WIN_GLOBAL_HPP
